Results from our forum

... bring them with me to the university in the fall and use their equipment. Not exactly willing to invest in an autoclave yet! Maybe I'll try the burner idea. Or just buy some disposable sterile plates. Thanks again. :)

... from your results I presume you aren't doing that. The main issue with petri dish contamination is airborne bacteria, if you get a Bunsen burner and work closely with it on a blue flame (not too close of course) it will increase the sterility of the area. This should hopefully reduce contamination, ...